Process for preparing methacrylic acid or methacrylic esters

Abstract

The present invention relates to a process for the preparation of methacrylic acid or methacrylic esters, comprising the process steps of IA) preparation of 3-hydroxyisobutyric acid by a process comprising the process step of bringing a cell which has been genetically modified in comparison with its wild type in such a way that it is capable of forming more 3-hydroxyisobutyric acid, or polyhydroxyalkanoates based on 3-hydroxyisobutyric acid in comparison with its wild type, into contact with a nutrient medium comprising, as carbon source, carbohydrates, glycerol, carbon dioxide, methanol, L-valine or L-glutamate under conditions under which 3-hydroxyisobutyric acid or polyhydroxyalkanoates based on 3-hydroxyisobutyric acid are formed from the carbon source, if appropriate, isolation of the 3-hydroxyisobutyric acid from the nutrient medium and also, if appropriate, neutralization of the 3-hydroxyisobutyric acid, IB) dehydration of the 3-hydroxyisobutyric acid with formation of methacrylic acid and also, where appropriate, esterification methacrylic acid. The invention also relates to a process for the preparation of polymethacrylic acid or polymethacrylic esters.

We claim: 
     
       1. A process for preparing a methacrylic acid or a methacrylic ester, comprising preparing a 3-hydroxyisobutyric acid by a process comprising:
 culturing a genetically modified cell which forms 3-hydroxyisobutyric acid, or polyhydroxy-alkanoate comprising 3-hydroxyisobutyric acid via a pathway employing succinyl-coenzyme A as an intermediate and methylmalonate semialdehyde as precursor in a nutrient medium comprising a carbon source under a condition wherein at least a portion of the carbon source is enzymatically converted to 3-hydroxyisobutyric acid or a polyhydroxy-alkanoate comprising 3-hydroxyisobutyric acid, 
 wherein the carbon source is at least one source selected from the group consisting of a carbohydrate, glycerol, L-valine, and L-glutamate; 
 wherein the genetically modified cell comprises: 
 (1) NCg11470, NCg11471, and NCg11472 genes encoding an enzyme E 1  which catalyses conversion of succinyl-coenzyme A to methylmalonyl coenzyme A; 
 (2) a gene of  S. tokodaii  encoding malonyl-coenzyme A reductase that provides enzyme activities of enzymes E 2  and E 3 , wherein the enzyme E 2  catalyses conversion of methylmalonyl-coenzyme A to methylmalonate, and the enzyme E 3  catalyses conversion of methylmalonate to methylmalonate semialdehyde; and 
 (3) a gene of  Thermus thermophilus  encoding an enzyme E 4  which catalyses conversion of methylmalonate semialdehyde to 3-hydroxyisobutyrate; 
 wherein the genes (1), (2), and (3) express respective enzymes which catalyze the formation of 3-hydroxyisobutyric acid by the genetically modified cells when the cells are cultured in a medium comprising a carbohydrate source; 
 optionally isolating the 3-hydroxyisobutyric acid from the nutrient medium; 
 optionally neutralizing the 3-hydroxyisobutyric acid; and 
 dehydrating the 3-hydroxyisobutyric acid, to obtain methacrylic acid and optionally, 
 esterifying the methacrylic acid; 
 wherein the genetically modified cell is  Corynebacterium glutamicum,    
 wherein the enzyme E 1  is a methylmalonyl-coenzyme A mutase of EC 5.4.99.2, 
 the enzyme E 2  is a methylmalonyl-coenzyme A hydrolase (EC 3.1.2.17) which catalyzes the conversion of methylmalonyl-coenzyme A into methyl malonate; 
 the enzyme E 3  is an aldehyde dehydrogenase (EC 1.2.1.3) or an aldehyde oxidase (EC 1.2.3.1); and 
 the enzyme E 4  is a 3-hydroxyisobutyrate dehydrogenase (EC 1.1.1.31). 
 
     
     
       2. A process of preparing polymethacrylic acid or polymethacrylic ester, comprising
 IIIA) preparing a methacrylic acid by the process according to  claim 1 , 
 IIIB) carrying out free-radical polymerization of the methacrylic acid, and optionally esterifying at least in part the carboxyl groups of the methacrylic acid or the carboxylate group of the methacrylate before or after the free-radical polymerization reaction. 
 
     
     
       3. The process of  claim 1 , wherein an activity of said enzyme E 1  is increased in comparison with its activity in a wild type cell. 
     
     
       4. The process of  claim 1 , wherein an activity of the enzymes E 2  and E 3  is increased in comparison with an enzyme activity in a wild type cell. 
     
     
       5. The process of  claim 1 , wherein the gene encoding said enzyme E 1  is from  Corynebacterium glutamicum  (ATCC13032) and comprises the nucleotide sequence of SEQ ID NO:1, the gene encoding said enzyme malonyl-coenzyme A reductase from  S. tokodaii  that provides enzyme activities of enzymes E 2  and E 3  comprises the nucleotide sequence of SEQ ID NO 3 and the gene encoding said enzyme E 4  is mmsB from  Thermus thermophilus.    
     
     
       6. The process of  claim 1 , wherein said enzyme E 1  comprises the amino acid sequence of SEQ ID NO:2 and said enzyme malonyl-coenzyme A reductase comprises the amino acid sequence of SEQ ID NO:4.